The objective of this research program will be directed towards an understanding of the regulatory mechanisms of hemoglobin switching at the molecular level. Fetal hemoglobin levels in peripheral venous blood will be determined using women with normal pregnancy and women with hydatidiform molar pregnancy. Fetal hemoglobin levels will be determined by an immunofluorescent antibody labeling technique. The levels of three chorionic polypeptide hormones, human choriogonadotropin (HCG), human chorionic somatomammotropin (HCS), and human chorionic thyrotropin (HCT) in sera of these patients will be measured. Effects of these polypeptide hormones, progesterone, serum from patients with hydatidiform mole and extracts from trophoblastic tissues of these patients on hemoglobin F production will be studied using adult marrow culture. Attempts will be carried out to isolate and characterize the putative components which may be responsible for stimulating fetal hemoglobin production in adult marrow cells.